The long summer (June through September) is characterized by intense heat and alternating dryness and humidity, with temperatures exceeding 55° C. Temperatures are moderate from November through May, although in winter temperatures may fall to 17° C, which is relatively cool for the latitude. Rainfall is negligible, averaging 100 millimeters per year, usually during the winter months, and falling in brief spills, filling the small ravines and the usually dry wadis. Sudden, violent dust storms occasionally descend on the peninsula.

The scarcity of rainfall and the limited underground water, most of which has such a high mineral content that it is unsuitable for drinking or irrigation, restricted the population and the extent of agricultural and industrial development the country could support until desalination projects began. Although water continues to be provided from underground sources, most is obtained by desalination of seawater.